Originally Posted by Jordan Smith
Originally Posted by Clarkm

It does have a problem a 2,500 feet elevation.
O2 and N2 scatter blue sunlight and make a background for the bullet to have a shadow.
There is not much O2 or N2 above me to make a shadow.
So I turn the pro chrono sideways and get a bullet shadow on a box.

Clark,

I think you’re misunderstanding the optical mechanism a little bit. While it’s true that the atmosphere scatters blue wavelengths more than other wavelengths in white light, which is why the sky “looks” blue, there is plenty of white light that reaches the Earth from the sun in a “line-of-sight” path.

My Pro Chrono works just fine at 5000 feet ASL, with or without diffusors.


I may be confused, there is always the danger of hidden variables. And I know you are scary smart. But here in Seattle at 300 feet, the sky is a bright blue and the chrono triggers. In MT at 2500 feet, a clear sky [looking straight up] looks black and the chrono will not trigger. But with a little cloud cover at the same spot at 2500 feet, it will trigger.

I can think of a hidden variable. Your chrono could have a trigger set to a more sensitive threshold than mine.

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